U.S. patent number 8,039,746 [Application Number 10/523,829] was granted by the patent office on 2011-10-18 for electric connector and cable.
This patent grant is currently assigned to Fujikura Ltd.. Invention is credited to Shigeru Ashida, Tomoyuki Shinohara.
United States Patent |
8,039,746 |
Ashida , et al. |
October 18, 2011 |
Electric connector and cable
Abstract
An electrical connector includes a terminal (11) fixed to a
connector housing (10). The electrical connector includes a
conductor (23) exposed from a covering (22) and having a connection
portion connected to a connection portion of the terminal (11). The
electrical connector includes a foam element (31) at a
predetermined foam ratio located around respective connection
portions of the conductor (23) and the terminal (11).
Inventors: |
Ashida; Shigeru (Chiba,
JP), Shinohara; Tomoyuki (Chiba, JP) |
Assignee: |
Fujikura Ltd. (Tokyo,
JP)
|
Family
ID: |
31711747 |
Appl.
No.: |
10/523,829 |
Filed: |
August 8, 2003 |
PCT
Filed: |
August 08, 2003 |
PCT No.: |
PCT/JP03/10154 |
371(c)(1),(2),(4) Date: |
February 08, 2005 |
PCT
Pub. No.: |
WO2004/015822 |
PCT
Pub. Date: |
February 19, 2004 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20050255741 A1 |
Nov 17, 2005 |
|
Foreign Application Priority Data
|
|
|
|
|
Aug 8, 2002 [JP] |
|
|
P2002-231440 |
|
Current U.S.
Class: |
174/88R |
Current CPC
Class: |
H01R
13/5216 (20130101); H01R 12/592 (20130101) |
Current International
Class: |
H01R
4/00 (20060101) |
Field of
Search: |
;174/88R,117F
;439/620 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
H02-253584 |
|
Oct 1990 |
|
JP |
|
H05-020944 |
|
Jan 1993 |
|
JP |
|
H06-249871 |
|
Sep 1994 |
|
JP |
|
2002-190215 |
|
Jul 2002 |
|
JP |
|
2002-214491 |
|
Jul 2002 |
|
JP |
|
Primary Examiner: Nguyen; Chau
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
The invention claimed is:
1. An electrical connector comprising: a conductor exposed from a
covering; a connection portion of the conductor connected to a
connection portion of a terminal; a connector housing receiving the
terminal; an impedance control means fixed on the connection
portions of the conductor and the terminal; and a second covering
that covers a part of the covering, the impedance control means and
a part of the connector housing, wherein the impedance control
means is a foam resin controlling an impedance in terms of a foam
ratio that is selected so that an impedance of the connection
portions substantially match the impedance of the covering of the
conductor.
2. The electrical connector according to claim 1, wherein the foam
resin functions as a capacitive capacitor.
3. The electrical connector according to claim 1, wherein
respective connection portions of the conductor and the terminal
are located in a cavity of the connector housing, wherein the
connector housing is made of a foamed resin.
4. The electrical connector according to claim 1, wherein the foam
ratio is greater than 0% and 80% or less.
5. The electrical connector according to claim 1, wherein the foam
resin has strength to maintain a structure thereof.
6. An electrical connector according to claim 1, wherein the foam
resin fills a surrounding space defined by the connection portions
and the second covering.
7. A method of fabricating an electrical connector, comprising:
connecting a connection portion of a terminal and a connection
portion of a conductor exposed from a covering to each other;
receiving the terminal in a connector housing; fixing impedance
control means on the connection portions of the conductor and the
terminal; and covering a part of the covering, the impedance
control means and a part of the connector housing with a second
covering; wherein the impedance control means is a foam resin
controlling an impedance in terms of a foam ratio that is selected
so that an impedance of the connection portions substantially match
the impedance of the covering of the conductor.
8. The method of fabricating an electrical connector according to
claim 7, wherein the foam resin is controlled to be approximate in
impedance to the covering.
9. The method of fabricating an electrical connector according to
claim 7, wherein the foam resin is molded to cover respective
connection portions.
10. The method of fabricating an electrical connector according to
claim 7, wherein the foam resin is formed into a predetermined
shape to be fitted to respective connection portions.
11. The method of fabricating an electrical connector according to
claim 7, wherein the foam resin is formed as a tape to be wound
around respective connection portions.
12. An electrical connector comprising: a cable comprising: an
electrical wire including a conductor exposed from a first
covering; a drain wire arrayed parallel to the electric wire; and a
jacket holding the electric wire and the drain wire; a connection
terminal having a connection portion connected to an end of the
conductor; an earth terminal having a connection portion connected
to an end of the drain wire; a connector housing receiving the
connection terminal and the earth terminal; and a second covering
located around a foam resin, wherein the foam resin is configured
to control an impedance in terms of a foam ratio that is selected
so that an impedance of the connection portion substantially
matches an impedance of a the first covering.
13. A cable comprising: an electric wire having a conductor exposed
from a covering; a connection portion of the electric wire
connected to a connection portion of a terminal; a connector
housing receiving the terminal; a foam element fixed on the
connection portions of the electric wire and the terminal; and a
second covering that covers a part of the covering, the foam
element and a part of the connector housing, wherein the foam
element is a foam resin controlling an impedance in terms of a foam
ratio that is selected so that an impedance of the connection
portions substantially match the impedance of the covering of the
electric wire.
14. A connector for a signal transmission cable, comprising: a
connector housing; a terminal fixed to the connector housing; a
cable conductor exposed from a covering and electrically connected
to the terminal by welding within the connector housing; an
impedance control means fixed on a connection of the terminal and
the cable conductor; and a second covering that covers a part of
the covering, the impedance control means and a part of the
connector housing, wherein impedance control means is a foam resin
controlling an impedance in terms of a foam ratio that is selected
so that an impedance of the connection of the terminal and the
cable conductor substantially match the impedance of the covering
of the cable conductor.
15. The connector for a signal transmission cable according to
claim 14, wherein the connection portions include a molten alloy
layer.
16. The method of fabricating a connector for a signal transmission
cable, comprising: welding a terminal and a cable conductor having
a covering to make a connection portion; inserting the terminal in
a housing; preparing a foamable resin; locating connection portions
of the terminal and the cable conductor in a die; feeding the
foamable resin into the die for extrusion to cover the connection
portion with a foam element; forming a second covering that covers
a part of the covering, the foamable resin and a part of the
housing, wherein foamable resin is configured to control an
impedance in terms of a foam ratio that is selected so that an
impedance of the connection portions of the terminal and the cable
conductor substantially match the impedance of the covering of the
cable conductor.
17. A method of fabricating a connector for a signal transmission
cable, comprising: welding a terminal and a cable conductor to each
other for connection; forming a pair of foam resin covering members
preliminarily formed into shapes which conform to an upper half
shape and a lower half shape of connection portions of the terminal
and the cable conductor; fitting said pair of covering members
around the connection portions of the terminal and the cable
conductor; and molding a resin for a connector housing around the
terminal, the pair of foam resin covering members, and the cable
conductor exposed from a covering, thus to form the connector
housing in a predetermined shape, wherein the foam resin configured
to control an impedance in terms of a foam ratio that is selected
so that an impedance of the connection of the terminal and the
cable conductor substantially match the impedance of the pair of
covering members.
18. The method of fabricating a connector for a signal transmission
cable, according to claim 17, wherein the foam resin has a
predetermined foam ratio selected to substantially match the
impedance of the connection portions with a covering of the cable
conductor.
19. A method of fabricating a connector for a signal transmission
cable, comprising: welding a terminal and a cable conductor for
connection; preparing a foam resin tape; winding the foam resin
tape a predetermined number of times around connection portions of
the terminal and the cable conductor to cover the connection
portions; molding a resin for a connector housing around the
terminal, the foam resin tape, and the cable conductor exposed from
a covering, thus to form a connector housing in a predetermined
shape, wherein the foam resin tape is configured to control an
impedance in terms of a foam ratio that is selected so that an
impedance of the connection of the terminal and the cable conductor
substantially match the impedance of the covering of the conductor.
Description
TECHNICAL FIELD
The invention relates to an electrical connector and a cable, and
more particularly relates to an electrical connector and a cable
for signal transmission having impedance characteristics.
BACKGROUND ART
An electrical connector has an insulation covered electric wire
having the end of a conductor, from which an insulator was removed.
The electrical connector has a connection terminal conducted and
connected with this end. The connection portion between the end of
the conductor and the connection terminal is protected by a plastic
connector housing (plastic cover), a polyvinyl chloride resin (PVC)
mold, or the like.
With the conductor covered with the insulator, the impedance of the
insulation covered electric wire is determined by the permittivity
of the insulator. However, the insulator is removed from the
terminal of the insulation covered electric wire, and the conductor
is exposed to conduct and connect to the connection terminal of the
electrical connector. Consequently, the impedance of this terminal
becomes different from the impedance of the insulation covered
portion.
Even if the connection portion between the end of the conductor and
the connection terminal is covered with resin mold, the impedance
of the connection portion is determined by complex factors, that
is, the shape of the connection portion, the terminal
configuration, the permittivity of mold resin material, and the
like. Impedance control to a predetermined value is difficult, such
as matching of the impedance of the connection portion to the
impedance of the insulation covered portion.
Adding to this, a signal transmission cable for high-speed
transmission called a high-speed cable is used by virtue of an
acceleration of the transmission speed in the interface cable of a
computer. This cable requires optimization of the impedance of the
electrical connector as a non-conventional electrical
characteristic. Thus, the impedance of an electrical connector is
controlled to an appropriate predetermined value as needed.
DISCLOSURE OF INVENTION
The mold configuration includes premold (primary mold) of the
connection portion between the end of the conductor and the
connection terminal. The configuration, having a secondary mold
over the premold, becomes the connector product. The primary mold
resin employs polyethylene (PE) or polypropylene (PP), for example,
is used, or a polyvinyl chloride resin (PVC) of the same quality as
the secondary mold resin material.
A basic object of this double mold is to form the primary mold with
a selected material which has better electrical characteristics
than that of the secondary mold and which is a resin material
moldable at a low temperature. Another basic object is to stabilize
the mechanical strength of the connection portion between the end
of the conductor and the connection terminal. This object is also
to mainly improve the mold appearance of the secondary mold. The
double mold is, on a rare occasion, used for the purpose of
improvement in insulation resistance or withstand pressure as the
required performance of the primary mold.
An object of this invention is to provide an electrical connector,
which has an impedance controlled to an appropriate predetermined
value, thus optimizing the impedance of the electrical
connector.
An electrical connector according to the first aspect of the
invention includes a terminal fixed to a connector housing. The
electrical connector includes a conductor exposed from a covering
and having a connection portion connected to a connection portion
of the terminal. The electrical connector includes a foam element
at a predetermined foam ratio located around respective connection
portions of the conductor and the terminal.
According to the first aspect, the impedance of the connection
portions of the conductor and the terminal is controlled with the
permittivity of the foam element. The permittivity of the foam
element is quantitatively determined by the permittivity of matrix
and the foam ratio, allowing the impedance of the connection
portion according to the foam ratio of the foam element to be
arbitrarily set. Thus, the loss on the connection portions is
reduced to provide an electrically stable electrical connector.
As a preferred embodiment, the foam element includes a resin, and
impedance of the foam element is closer to impedance of the
covering, compared with a non-foamed resin.
As a preferred embodiment, the foam element includes a foam
resin.
As a preferred embodiment, the foam element functions as a
capacitive capacitor.
As a preferred embodiment, respective connection portions of the
conductor and terminal are located in a cavity of the connector
housing, and the connector housing is made of a foam resin.
As a preferred embodiment, the foam ratio of the foam element is
greater than 0% and 80% or less.
As a preferred embodiment, the foam element has strength to
maintain a structure thereof.
A method of fabricating an electrical connector according to the
second aspect of the invention includes the step of connecting a
connection portion of a terminal and a connection portion of a
conductor exposed from a covering to each other. The fabrication
method includes the step of covering respective connection portions
of the terminal and the conductor from therearound with a foam
element at a predetermined foam ratio.
According to the second aspect, the conductor is covered with the
foam element by one operation, which provides a mechanically stable
product.
As a preferred embodiment, the foam element is controlled in
impedance to be approximate to the covering.
As a preferred embodiment, the foam element is molded to cover
respective connection portions.
As a preferred embodiment, the foam element is formed into a
predetermined shape to be fitted to respective connection
portions.
As a preferred embodiment, the foam element is formed as a tape to
be wound around respective connection portions.
An electrical connector according to the third aspect of the
invention includes a cable. This cable includes an electric wire
including a conductor exposed from a first covering. The cable
includes a drain wire arrayed parallel to the electric wire. The
cable includes a jacket holding the electric wire and the drain
wire. The electrical connector includes a connection terminal
having a connection portion connected to an end of the conductor.
The electrical connector includes an earth terminal having a
connection portion connected to an end of the drain wire. The
electrical connector includes a connector housing receiving the
connection terminal and the earth terminal. The electrical
connector includes a foam resin located around the end of the
conductor, the connection portion of the connection terminal, the
end of the drain wire and the connection portion of the earth
terminal. The electrical connector includes a second covering
located around the foam resin.
A cable according to the fourth aspect of the invention has an
electric wire having a conductor exposed from a covering. The cable
has a connector including a terminal having a connection portion
connected to a connection portion of the conductor and fixed to a
connector housing. The cable includes a foam element at a
predetermined foam ratio located around respective connection
portions of the conductor and the terminal.
A connector for a signal transmission cable according to the fifth
aspect of the invention includes a connector housing. The connector
includes a terminal fixed to the connector housing. The connector
includes a cable conductor electrically connected to the terminal
by welding within the connector housing. The cable includes a foam
element covering a connection portion of the terminal and the cable
conductor within the connector housing.
As a preferred embodiment, the connection portions include a molten
alloy layer.
A method of fabricating a connector for a signal transmission cable
according to the sixth aspect of the invention includes the step of
welding a terminal and a cable conductor to each other for
connection. The fabrication method includes the step of preparing a
foamable resin. The fabrication method includes the step of
locating connection portions of the terminal and the cable
conductor in a die; feeding the foamable resin into the die for
extrusion to cover the connected terminal and the conductor from
therearound with a foam element at a predetermined foam ratio, thus
to form a connector housing in a predetermined shape.
A method of fabricating a connector for a signal transmission cable
according to the seventh aspect of the invention includes the step
of welding a terminal and a cable conductor to each other for
connection. The fabrication method includes the step of fitting
said pair of covering members around the connection portions of the
terminal and the cable conductor. The fabrication method includes
the step of molding a resin for the connector housing around the
terminal, the foam resin, and the cable conductor exposed from a
covering, thus to form a connector housing in a predetermined
shape.
A method of fabricating a connector for the signal transmission
cable according to the eighth aspect of the invention includes the
step of welding a terminal and a cable conductor for connection.
The fabrication method includes the step of preparing a foam resin
tape. The fabrication method includes the step of winding the foam
resin tape a predetermined number of times around connection
portions of the terminal and the cable conductor to cover the
connection portions. The fabrication method includes the step of
molding a resin for a connector housing around the terminal, the
foam resin tape, and the cable conductor exposed from a covering,
thus to form a connector housing in a predetermined shape.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view of a cable according to the first
embodiment of the invention.
FIG. 2 is a plan view of an electrical connector of FIG. 1.
FIG. 3 is a side view of the electrical connector of FIG. 1.
FIG. 4A is a sectional view taken along IVA-IVA of FIG. 2.
FIG. 4B is a sectional view taken along IVB-IVB of FIG. 2.
FIG. 4C is an enlarged view of a connection portion of FIG. 4B.
FIG. 5 is a graph illustrating the impedance versus foam ratio of a
foam resin.
FIG. 6 is a view illustrating the impedance profile of the
electrical connector of FIG. 3.
FIG. 7 is a block diagram illustrating the method of covering a
connection portion of FIG. 3.
FIGS. 8A and 8B are side views for illustrating spot welding of
FIG. 7.
FIG. 9 is a plan view of an electrical connector according to the
second embodiment of the invention.
FIG. 10 is a side view of the electrical connector of FIG. 9.
FIG. 11 is a plan view of an electrical connector according to the
third embodiment of the invention.
FIG. 12 is a side view of the electrical connector of FIG. 11.
FIG. 13 is a perspective view of an electrical connector according
to the fourth embodiment of the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
With reference to the attached drawings, embodiments of this
invention are hereunder described in detail.
Referring to FIG. 1, a cable 1A of a first embodiment includes
electrical connectors 5 and an assembled cable 20 which are
connected to each other. The connector 5 includes a resin connector
body or a connector housing 10. The connector 5 includes a
plurality of parallel-arranged connection terminals 11 within the
connector housing 10. The terminals 11 have contacts 11a protruding
from the connector housing 10.
The connector housing 10 has dimensions of, for example, 12 times
10.sup.-3 m in the longitudinal direction, 14 times 10.sup.-3 m in
the transverse direction, and 3.5 times 10.sup.-3 min the thickness
of the terminal 11. The contacts 11a of the terminals 11 protrudes
from the connector housing 10, with a length of, for example, 2.6
times 10.sup.-3 m. The distance between contacts 11a, for example,
is 1.27 times 10.sup.-3 m.
Referring to FIG. 4A, the cable 20 includes two sets of insulation
covered electric wires 21 arranged in parallel with each other. The
covered electric wire 21 includes conductors 23 covered with an
insulator 22. Each of the covered electric wires 21 includes bare
wire drain wires 24 on the sides. The drain wires 24 and the
covered electric wire 21 are enclosed by aluminum foil 27. The
cable 20 includes a jacket 29 sheathing around the foil 27. At the
end portion of the covered electric wire 21, the insulator 22 is
removed to expose the end of the conductor 23. Referring to FIGS. 2
and 3, the end of the conductor 23 is also connected to a
corresponding connection terminal 11, using soldering or spot
welding. The end of the drain wire 24 is connected with a
corresponding earth terminal 11 by soldering or spot welding.
Referring to FIG. 4B and FIG. 4C, the contact 11a of the connection
terminal 11 and the end of the conductor 23 have a connection
portion 81. The end of the earth terminal 11 and the drain wire 24
have a connection portion. The connection portion 81 and the
connection portion include the region of the cable or the covered
electric wire in which part or the whole of the covering (including
a cable jacket) is removed, and the region of the terminal of the
connector connected to the conductor of the region.
With regard to the connection portion 81 between the connection
terminal 11 and the conductor 23, and the connection portion
between the earth terminal 11 and the drain wire 24, the whole
thereof is, as its primary molding, collectively covered by molding
with a molded foam resin 31. In other words, the foam resin 31 is
filled around the conductor 23, the drain wire 24, the connection
terminal 11, and the earth terminal 11. The foam resin 31 includes
uniformly dispersed gas bubbles 31a. The gas bubbles 31a function
as a capacitance or impedance control means.
The electrical connector 5 is further covered by molding resin 32,
such as polyvinyl chloride, as its secondary molding, thereby
forming the product into a shape.
The foam resin 31 is foamed polyurethane, foamed polystyrene,
foamed polypropylene, foamed polyethylene, foamed polyvinyl
chloride, foamed ABS resin, foamed urea resin, foamed phenol resin,
or the like. The foam ratio of the resin 31 is set according to the
required impedance. The foam ratio means the ratio (%) of the gas
bubble to the whole cubic volume. The foam ratio is measured by
Archimedes' principal as in the case of porosity.
The permittivity of the foam resin 31 is quantitatively determined
by the permittivity and the foam ratio of the resin material itself
of the foam resin 31. Therefore, the foam ratio of the foam resin
31 sets the impedance of the connection portion 81 between the end
of the conductor 23 and the contact 11a of the connection terminal
11 at a desired value. Moreover, coincidence of the impedance in
the connection portion 81 with approximation to the impedance of
coverings 22 and 29 reduces any loss on the connection portion
81.
Referring to FIG. 5, experiments on the relationship between foam
ratio of the foam resin and impedance in the primary mold of the
cable 1A were performed. As raw materials, polypropylene and
foaming agent were mixed at a predetermined weight ratio, which was
foamed. In this experimental example, in the case where the weight
ratios of polypropylene and the foaming agent were 100 to 0, 97 to
3, 95 to 5 and 93 to 7, foam ratios were 0%, 5%, 10%, and 20% in
order. As for the impedance, the minimum value in the measured
values was adopted.
As a result, the impedance increased in the foam ratio from 0 to
15% at a given slope. The foam ratio over 15% gradually reduced the
slope of the impedance. The foam ratio over 60% rendered the
impedance approximately constant.
The impedance of the foam resin with a foam ratio of 20% or more
approached approximately 100.OMEGA. as a standard value of covering
impedance. Therefore, the foam ratio is preferably 20% or more. On
the other hand, in terms of achieving high strength of the foam
resin, the foam ratio is preferably 60% or less. The foam ratio
over 80% causes insufficient strength, which is unable to maintain
the mold structure of the foam resin.
From the above, it was confirmed that adjustment of the foam ratio
of the foam resin allows for control of the impedance. This is
generally based on the inverse proportion of characteristic
impedance to the square root of .epsilon. (permittivity). In other
words, if the shape factor of the foam resin is specified in
advance, selection of the permittivity of the foam resin with the
foam ratio uniquely determines the impedance.
Referring to FIG. 6, the impedance profile of the cable 1A is
described. The impedance was measured in the longitudinal direction
of the cable 1A, using time domain reflectometry (TDR).
The abscissa axis indicates the positions respectively
corresponding, from the left to the right, to a board, a connector
housing 10, a cable 20, a primarily molded connection portion 81, a
covered electric wire 22, a cable 20. The ordinate axis indicates
the impedance. P.sub.1 is the impedance profile of the cable 1A
covered with the foam resin 31. The impedance of the board is
107.8.OMEGA.. The impedance of the cable 20 is 99.5.OMEGA.. The
impedance of the connection portion 81 and the periphery thereof
indicates values close to the impedance of the cable 20. The
significant variation in the impedance in the connector housing 10
arises from the connection between the connection terminal 11 and
the board. On the other hand, P.sub.0 is the impedance profile of
the cable 1A in which the connection terminal 11 of the connection
portion 81 and the conductor 23 are not covered. The peaks of
5.OMEGA. or more to the cable were identified in the connection
portion 81 of connection terminal 11 and the conductor 23, and the
periphery thereof.
Referring to FIG. 7, the covering method in the connection portion
is described.
A foaming agent and a resin are mixed at a predetermined weight
ratio to prepare a foamable resin (S1). The foaming agent employs,
for example, ADCA (Azodicarbonamide), DPT
(Dinitrosopentamethyleneteramin) or, OBSH
(benzenesulfonylhydrazide).
At the end portion of the cable 20, the jacket 29 is given a cut-in
and is removed to expose a covered electric wire 21. The insulator
22 of the covered electric wire 21 is removed to expose a conductor
23(S2). The end of the conductor 23 and the contact 11a of the
terminal 11 are soldered to each other to form a connection portion
81. The drain wire 24 and the earth terminal 11 are soldered to
form a connection portion (S3).
The connection portion 81 is placed in a die. With pressure and
heat (approximately from 150 degrees Celsius to 250 degrees
Celsius) applied, the foamable resin is fed into the die for
extrusion. During the extrusion, the foaming agent reacts to
produce gas bubbles, turning the foamable resin into the foam resin
31. The foam resin 31 is filled around the connection terminal 11
and the conductor 23 of the connection portion 81, and around the
drain wire 24 and the earth terminal 11. This step forms a primary
mold (S4). Next, PVC (polyvinyl chloride) is molded around the foam
resin 31, the covered electric wire 21 and the connector housing 10
to form a secondary mold 32 in a predetermined shape (S5).
As another method, the connection terminal and the conductor 23 are
spot welded to form the connection portion 81 (S6).
Referring to FIGS. 8A and 8B, the spot welding is described. In
FIG. 8A, the connecting device includes a pair of electrodes 71
having a positive electrode 71a and a negative electrode 71b, which
are spaced from each other. The electrodes 71a and 71b are movable
in the vertical direction. Alternatively, in FIG. 8B, a pair of
electrodes 71a and 71b may respectively have the terminal 11 and
the conductor 23 to be connected, interposed therebetween from the
above and below. The pair of electrodes 71a and 71b are movable in
the vertical direction, respectively.
With the electrodes 71a and 71b pressed against the conductor 23
toward the connection terminal 11, current is applied between the
electrodes 71a and 71b through the conductor 23 and the connection
terminal 11. In this process, current is applied through the
surface contact resistance between the conductor 23 and the
connection terminal 11 to produce intense heat. The intense heat
melts the contact surface between the connection terminal 11 and
the conductor 23, and forms what is called a nugget, which is a
molten alloy layer, (when the cable conductor 23 is plated with
silver, the molten alloy becomes silver-copper alloy). This nugget
connects the connection terminal 11 and the conductor 23 to each
other, forming a connection portion 81.
After that, in Step S4, the connection portion 81 is placed in the
die, and the foamable resin is fed into the die for extrusion, with
pressure and heat (approximately 150 degrees Celsius to 250 degrees
Celsius) applied, forming a primary mold. Next, in Step S5, PVC
(polyvinyl chloride) is molded around the foam resin 31 to form the
secondary mold 32 in a predetermined shape.
Note that, in place of molding (S4), the foam resin tape may be
wound around this connection portion 81, and the terminal 11 and
conductor 23 in the periphery thereof (Refer to S7 and FIGS. 11 and
12).
With the above, setting of foam ratio of the foam resin 31 to an
appropriate predetermined value controls the impedance of the
electrical connector 5. This control of the embodiment optimizes
the impedance of the electrical connector 5 as required.
Further, the spot welded connector achieves the following
advantages, compared with a solder welded connector.
1. Formation of the alloy layer in the contact by welding allows
the structure or the composition between the cable conductor and
the contact to be gradually or continuously changed. This
suppresses signal reflection and the like and reduces attenuation
when a high frequency signal is transmitted between the conductor
and the contact.
2. Particularly, the transmission signal with a frequency of 1000
MHz (1 GHz) or more significantly reduces connection loss on weld
cable, compared with soldered cable. The frequency of 2500 MHz (2.5
GHz) or more allows for the difference between both to be more
remarkable.
3. The crosstalk among signal lines is significantly reduced. To be
more specific, for example, when a noise signal with a voltage of 6
V is applied through the neighboring signal line, the ratio in
occurrence of errors in a soldered connecting signal line is 1 bit
to about 1000 bits, while the ratio in occurrence of errors in a
weld signal line is 1 bit to about 10.sup.7 bits. For this reason,
the ratio in occurrence of errors in a weld signal line is
significantly reduced compared with the ratio in occurrence of
errors in a soldered signal line.
4. The joint strength increases.
5. The smaller electrical loss allows the transmission speed to be
at a higher speed.
6. The transmission characteristics (impedance, crosstalk, and the
like) are stabilized.
Second Embodiment
Referring to FIG. 9 and FIG. 10, a cable 1B of a second embodiment
is described. Hereunder, members and parts corresponding to FIG. 2
and FIG. 3 are designated by the identical reference numerals and
codes, and the description is omitted.
An electrical connector 5 includes a pair of covering parts 33A and
33B separated into halves. The parts 33A and 33B are formed in such
shapes in advance so as to conform to the shape of a connection
portion 81 between a connection terminal 11 and the end of a
conductor 23, as well as the connection portion between an earth
terminal 11 and the end of a drain wire 24. The covering parts 33A
and 33B are covered and fitted to the whole of respective
connection portions 81.
In this embodiment, setting of the foam ratio of the foam resin
constituting the covering part half bodies 33A and 33B controls the
impedance of the electrical connector 5 to an appropriate
predetermined value. This embodiment optimizes the impedance of the
electrical connector 5 according to requirements, similarly to
embodiment 1.
Third Embodiment
Referring to FIG. 11 and FIG. 12, a cable 1C of a third embodiment
is described.
On an electrical connector 5, a foam resin tape 34 is wound and
fitted around a connection portion 81 between a connection terminal
11 and the end of a conductor 23, as well as a connection portion
between an earth terminal 11 and an end of a drain wire 24. The
entire connection portion 81 is covered with foam resin tape
34.
In this embodiment, setting of the foam ratio of the foam resin
constituting the foam resin tape 34 appropriately controls the
impedance of the electrical connector 5 to a predetermined value.
This embodiment optimizes the impedance of the electrical connector
5 according to requirements similarly to embodiment 1.
Fourth Embodiment
Referring to FIG. 13, a cable 1D of a fourth embodiment is
described.
An electrical connector 1D includes an insulation covered electric
wire 40, comprising a conductor 41 covered with an insulator 42.
The conductor 42 at the end portion of the covered electric wire 40
is removed to expose a conductor 41. The end of the exposed
conductor 41 has a solderless terminal 51 crimped thereto. Together
with the solderless terminal 51, the end of the covered electric
wire 40 is inserted into and fitted in a connector housing 60.
The connection portion between the end of the conductor 41 of the
covered electric wire 40 and the solderless terminal (connection
terminal) 51 is housed within the connector housing 60. The
connector housing 60 is made from a foam resin in which the foam
ratio has been adjusted.
Thus, in this embodiment, setting of the foam ratio of the foam
resin constituting the connector housing 60 appropriately controls
the impedance of the electrical connector 5 to a predetermined
value. For this reason, this embodiment optimizes the impedance of
the electrical connector according to requirements similarly to
embodiment 1.
INDUSTRIAL APPLICABILITY
The electrical connector and cable of this invention are useful for
connection with electrical machineries and apparatus in the field
of information communications, electronics, or automobiles.
Furthermore, the connector with lower loss is useful for electrical
machineries and apparatus with a number of connection
positions.
This invention is not limited to the embodiments, and variations
and modifications thereof can be made by the knowledge level of
those skilled in the art.
Contents of Japanese patent application 2002-231440 (filed Aug. 8,
2002) are incorporated by reference in this application.
* * * * *